Early Friday morning, the Keolis crew in Worcester discovered a problem with one of the layover sets. A replacement train set was dispatched from Boston to replace the broken down set. While the 'extra' was outbound to Worcester, the original set that was thought to be broken was either fixed or made operational. It was used as the equipment for P506 and departed Worcester on time. Therefore the 'extra' from Boston was not needed and it went back inbound to Boston as a non-revenue 'extra' move.

By Framingham, the 'extra' was operating just ahead of P508 - confusing passengers waiting for P508 when it didn't stop. It then passed P506 near West Newton. Good job Keolis fitting this extra inbound move without delaying the normal schedule!

This also could explain why B725 went through Framingham early. B725 is a CSX freight train from Attleboro to Framingham - passes through Medfield and Sherborn before crossing Route 135 in Framingham near the old Chicken Bone restaurant. From there, after joining the mainline Framingham Worcester tracks, it just goes west over Route 126 and into the freight yard between Winter Street and Fountain Street in Framingham ("Nevins Yard"). [The freight cars then eventually go west to Selkirk NY (near Albany) on a different manifest train (Q437) with different engines, but now I'm just getting carried away.]

Usually, B725 is held south of Blandin Avenue (so it doesn't block that crossing) until after P506 departs Framingham. Then the dispatcher gives it clearance and it moves up and across both Route 135 and the mainline track 2 - and travels west on track 1 through Framingham station. This timing allows it to move through without affecting commuter rail trains - it is in Framingham between P506 and P508 and clears off of track 1 before outbound P505 arrives in Framingham at 7:44 AM.

But on Friday 5/29, B725 made its move through Framingham AHEAD of P506, which I thought was odd. But in the context of the 'extra' story, it makes sense - they needed to get B725 out of the way so they could use the 'gap' time between P506 and P508 to move the 'extra' through Framingham inbound. It's fun to reverse engineer the dispatch decisions!

Ugh! Here we go again. There are only three seasons on the Framingham - Worcester line: frozen (no trains), summer (heat restrictions), and fall ("slippery rail" - more about that some other time).

The MBTA has a pretty good explanation of this issue here, but I've got some more technical details.

Basic physics: make something cold and it shrinks, make something hot and it expands. The Framingham - Worcester line, as most rail lines nowadays, is constructed with 1/4 mile long pieces of continuous rail. That's correct, they come from the factory as 1/4 MILE long pieces. This is a pretty good video of how the rail is transported and laid out: https://www.youtube.com/watch?v=5xxVD2L_veM And here is a picture of a rail train:

If that big hunk of metal gets too hot, it can expand to the point where it will create a 'sun kink' - a buckle. Here is a sun kink:

That will probably derail a train going any speed.

A piece of rail has a "neutral" temperature ("rail neutral temperature" (RNT)) - the temperature at which it is neither in compression or tension. Once it is anchored down at this temperature, any changes in temperature create stress in the rail. Too much compression stress (from expansion in heat) = sun kink. The general rule of thumb is that if the rail temperature gets 40 degrees above RNT, there is a chance of a sun kink. Too much tension stress (from shrinkage in cold) = a broken rail. The good thing about a broken rail is that it usually breaks the track 'circuit' and changes all the signals to red. So there is some mitigation for the cold side of RNT. There is also evidence that rails are better able to stretch than compress - meaning you have more 'room' on the cold side of RNT than the hot side. In other words, a higher RNT is more desirable.

There has been much research into this topic, and the Federal Railway Administration (FRA) now requires all railroads to outline their plan for managing the risk of CWR (continuously welded rail). The target RNT in our area is now 105. Note that this is the RAIL temperature - not the air temperature. Everything we're talking about here is the temperature of the rail - which can be quite a bit higher than air temperature on a sunny day.

Prior to the MBTA purchase of the entire line, CSX dispatched all the trains. They had a policy of limiting speeds according to hot temperatures, with the theory that a slower train does a number of things:1) does not impart more heat onto the tracks by the faster friction of speeding train;2) allows more reaction time for an engineer to react to a sun kink; and3) mitigates the chance of a derailment over a sun kink (slower train has better chance of dealing with a track defect).

Now that the MBTA owns the entire line and dispatches it, they can set and follow their own policy. However, their policy has to follow some logic or reasoning to comply with the FRA rules. For whatever reason, CSX or Conrail did not record or have the RNT of the Framingham - Worcester line. With an unknown RNT, the MBTA is forced to 'play it safe' and slow trains down like CSX did.

The good news is that the MBTA is spending a few million dollars to fix this situation on the Framingham Worcester line. Details are here. The "destressing project" essentially raises the RNT to a documented 105 degrees. The rail is released from the ties and heated to the new RNT. This usually requires cutting a small segment from the rail to allow it room to expand. Once it is at the new desired RNT, it is reaffixed to the ties and welded to the next section.

Note that they are only fixing track 2 from Boston to Framingham and track 1 from Framingham to Worcester. These are the tracks that carry MOST outbound evening commuter trains. So the project will fix the delays for MOST outbound trains in the evening, but it doesn't fix everything.

And yes, this is a real problem. The following accidents have been blamed on sun kinks:

Prior to October 4, 2012, the Class 1 freight railroad CSX owned the tracks from Worcester to Framingham (MBTA already owned Framingham to Boston). CSX dispatched all the trains from Worcester to Boston (freight and passenger) from their dispatch center in Selkirk NY (near Albany). Since they dispatched the trains, they had some control over the name of the trains. Their system and rules required leading letters on all train numbers, and "P" was used for passenger trains. [This system still exists on CSX - for example, T & U are coal trains, V are empty grain trains...]So for many years, all the MBTA commuter rail trains on the Framingham Worcester line had a "P" in front of the number. You can see the "P" in the old schedules. The Framingham Worcester line was the only MBTA commuter rail line with the "P." After the MBTA bought the tracks from Worcester to Framingham, they eventually took over dispatching the line from the MBTA dispatch theatre in South Station. And at that time, since they were no longer governed by CSX rules, they removed the "P" from the train names.So why do I keep using the "P" in my Twitter posts? I think it helps to clarify that I'm talking about a train number rather than a time. Most people talk about their train according to its departure time - which isn't helpful for the rest of us who may board at a different station at a different time. Since the Framingham Worcester line trains all start with a "5," I think that using the "P" is especially helpful in the afternoon - for example, train P531 departs South Station at 5:35 PM. So some people might get train 531 confused with train 583 which departs South Station at 5:30 PM.So thanks CSX - I'm keeping your naming convention!By the way, the South Station dispatch theatre is really cool. My really bad picture of it is here:http://photos.nerail.org/showpic/?photo=2003112223061020889.jpg

<NOTE: As of 6/8/2015, this table is no longer current. Read more recent blog posts for accurate "Turn Table." But the explanation of what this is (below) is still accurate. The "Turn Table" now has its own page here.><This post edited on 5/25/15 to move the list to the top of the post. Explanation of what this is all about is below.><This post edited on 5/28/15 to add discussion regarding 581>

[581 note added 5/28/15]581 is a non-revenue move that departs Boston at 4:45 AM and arrives in Worcester at 5:53 AM. These times can be helpful for us...theoretically, if it is after 4:45 AM and MBTA / Keolis has NOT cancelled 582, there is a good chance it will operate, since the equipment has probably left Boston en route to Worcester. That theory is only partially true since the following things could happen:1) MBTA / Keolis decides to delay sending out the cancellation notice for 582. 2) 581 might break down somewhere between Boston and Worcester or in Worcester.3) If some other layover equipment in Worcester is dead, MBTA / Keolis may decide to use the 581 / 582 equipment from Boston as a different train. I'm not sure that this has or would ever happen, but it is a possibility.

_________________________original post:

Recently on Twitter a fellow rider and I had a discussion about trying to predict if an inbound train would be late based on the lateness of an outbound train. This conversation prompted me to go through and figure out (and write down) the whole equipment usage for the Framingham Worcester line. Here it is...with some explanation.

First of all, we need to get some definitions out of the way:"Equipment" (as used in this post) = one train set, consisting of a locomotive and coach cars. "Turn" = the process of changing one set of equipment from an outbound to an inbound (or vice versa) train."Non-revenue" = movement of a train set from one place to another, BUT without passengers. A non-revenue move is a regularly 'scheduled' move with specific times, but isn't on the public MBTA schedule (it is on the employee timetable). Non-revenue moves also don't show up on the GPS tracking apps. "Layover" = overnight 'parking' for a train set on a dedicated siding where it can be plugged into ground power. At the current time, the Worcester MBTA yard has capacity to layover 4 train sets. No trains currently layover in Framingham or anywhere else on the line.

As I noted on Twitter, it is impossible to predict turns at South Station. Equipment is used interchangeably (well almost, there are some restrictions or considerations) on all south side lines. In other words, the equipment used on Framingham / Worcester throughout the day does NOT stay dedicated to the Framingham / Worcester line. A set arriving at South Station from Worcester may go back out to Needham or Providence, and a set originating in South Station bound for Worcester may have come from Providence or Needham or elsewhere. I'm sure there is a master plan of entire south side turns, but I'll bet changes have to made almost daily to accommodate late (or broken) trains. Therefore, since the South Station turns are so dynamically managed, it wouldn't help us very much to understand the entire south side master plan. But it is worth noting that delays on other lines CAN result in delays on the Framingham / Worcester line.

However, at Framingham and Worcester, the turns are very predictable and can help us understand delays. So without further rambling, here is the entire schedule of weekday equipment usage on the Framingham / Worcester line. The list above notes the location of the turn and the duration of the turn (the difference between the scheduled arrival time of the outbound train and the scheduled departure time of the inbound train). The duration of the turn can help us understand the impact of a delay. For example, if train 513 is only delayed 5 minutes, it might not delay the schedule of 520. But if 513 is delayed 30 minutes, it will almost certainly delay the schedule of train 520.

Acknowledgements: I first posted this to the railroad.net forum for confirmation and clarification of some aspects of my list. Thanks to the contributors there.

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As of late October 2017, the author is an MBTA employee. Blog posts prior to that time were created when I was NOT affiliated with the MBTA nor Keolis and therefore were my own opinion. Blog posts after October 2017 are my own personal statements and do not represent any official position or opinion of the MBTA and should not be construed as having been endorsed by the MBTA.